Because the usable frequency spectrum is finite, modern wireless communication networks began as viable public communication means with the adoption of frequency reuse schemes. In a typical “cellular” communication network, many low-powered “cells” provide radio communication to access terminals (ATs) within the cell's limited range. Each cell generally has a certain number of radio channels allocated for its use. Each neighboring cell may also have a certain number of radio channels allocated for their use. The early frequency reuse schemes provided that the frequency of channels used in a first cell could be reused in another cell as long as that other cell was far enough away from the range of the first cell to avoid channel interference. As ATs crossed into new cells there was a complicated hand-off that occurred where the communication session was changed from the original channel to a new channel provided in the new cell.
In modern wireless communication systems, coding and other sophisticated signal processing techniques allow some frequencies to be reused in neighboring cells or sectors. Moreover, modern networks typically use fixed channel assignment (FCA), in which each sector allocates channels to the ATs within the sector. Thus, there may be occasion in which two neighboring sectors assign the same channel to two different ATs. This can be a problem if the two ATs are close enough to experience same channel interference from the other AT's communication session. It may also be a problem during handoff when an incoming AT is on the same channel as an AT already in the sector. This sector-centered system may result in channel collisions between cells, slower detection by the access node (AN) of a call request from an AT, and delayed paging from the AN to the AT. Collisions and call delay often lead to customer dissatisfaction which could eventually lead to lower revenues for the service provider.